Psoriatic Arthritis vs. Gout: What Are the Differences?

From verywellhealth.com

Psoriatic arthritis (PsA) and gout are types of inflammatory arthritis that cause pain and swelling of the fingers, toes, knees, ankles, and other joints. While they have some similar symptoms and causes, they are very different conditions and are managed and treated differently.

This article will discuss the different symptoms of PsA vs. gout, what causes these conditions, how they are diagnosed and treated, and why PsA might increase your risk for gout. 

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Symptoms

The symptoms of PsA and gout can sometimes overlap, so it is important to understand the symptoms specific to each condition.

Psoriatic Arthritis

• Pain and stiffness in multiple joints

• Affected joints on one or both sides of the body

• Large joint involvement: Especially the lower extremities

• Nail involvement: Nail pitting, crumbling, and ridging, and nailbed separation

• Psoriasis skin symptoms

• Spine involvement: Stiffness and pain in the back or neck, and difficulty with bending

• Enthesitis (inflammation of connective tissue at joints), especially of the back of the heels and the soles of the feet

• Dactylitis (extreme swelling of fingers and toes)

• Eye inflammation

  
  

Gout

• Intermittent episodes of sudden red, hot, swollen joints

• Pain in the big toe, with warmth and redness

• Pain and swelling of other joints

• Polyarticular symptoms (gout attack in more than three joints)
  

• Tophi (lumps in and around the joints)

• Spine or sacroiliac (connecting pelvis to lower spine) joint involvement is rare

• Lingering discomfort

• Warmth and redness of affected joints

• Limited range of motion

Psoriatic Arthritis

PsA affects less than 1% of the American population. While this percentage might seem small, people with the inflammatory skin condition psoriasis account for many of the PsA cases. Psoriasis causes an overproduction of skin cells that pile up on the skin as plaques, red patches covered in silvery scales.

According to the National Psoriasis Foundation, nearly one-third of people with psoriasis will develop PsA. If you have psoriasis and develop joint pain, reach out to your healthcare provider to be assessed for PsA.

The most common symptoms of PsA are:

• Pain and stiffness in multiple joints
• Inflamed joints on one or both sides of the body
• Large joint involvement: Including in the lower extremities, such as the knees and ankles, although any joint can be affected by PsA
• Nail involvement: Nail pitting, crumbling, and ridging, and nail bed separation
• Skin symptoms: Similar to what is seen in psoriasis
• Spine involvement called psoriatic spondylitis: Causes stiffness and pain in the back or neck, and difficulty with bending
• Enthesitis: Tender spots in the entheses, where the tendons and ligaments join the bone, commonly affecting the backs of the heels and the soles of the feet
• Dactylitis:  Inflammation of the fingers and toes, sometimes called “sausage digits” because the fingers and toes can resemble small sausages
• Eye inflammation: Such as uveitis, an eye condition that causes eye redness and pain, blurred or cloudy vision, sensitivity to light, and vision 

Gout

Gout is characterized by intermittent episodes of sudden red, hot, swollen joints. People with gout also experience symptom-free periods. A gout attack can last from seven to 14 days. Gout attacks often start in the middle of the night, so a person can be awoken by pain without any warning.

Symptoms of gout include:

• Pain in the big toe: The first metatarsophalangeal joint of the big toe is the most affected joint. and this is sometimes called podagra. Excruciating pain can be felt with the slightest touch (such as bedding touching the toe). Additional symptoms are warmth and redness of the big toe.
  
• Pain in other joints: Any joint can be affected by a gout attack, and it can be more than one joint at a time (polyarticular). Other frequent sites for a gout attack are the feet, ankles, knees, wrists, and elbows. Polyarticular attacks may occur in 15%–40% of people with gout, especially women.
• Lumps around the joints: Tophi are lumps formed by mounds of uric acid crystals below the skin and around the joints. They are common in people whose gout is severe or chronic. Ongoing inflammation can cause tophi lumps, which can contribute to bone and cartilage destruction.
• Spine involvement: While rare, gout can affect the spine, especially the lumbar spine (in the lower back). It can also affect a sacroiliac joint, one or two joints that connect the sacrum at the base of the spine with the hip bone.
  
• Lingering discomfort: Even after the worst part of the gout attack has passed (peak is 12–24 hours after onset), some joint discomfort can last for days or weeks. For people with severe attacks or chronic gout, gout attacks might last longer and affect more joints.
• Warmth and redness of affected joints can occur.
  
• Limited range of motion: As the gout attack progresses, it may be harder to move joints as you normally would.

PsA–Gout Connection

People with psoriatic disease (PsA and/or psoriasis) have an increased risk of developing gout. This connection has been known for decades. Researchers think this is because of uric acid, which forms when the body breaks down purines found in human cells and many foods.

In people with PsA and psoriasis, uric acid might be to blame for skin cell overproduction and systemic inflammation. In people with gout, that uric acid builds up in and around joints.

A study reported in 2014 in the journal Drug Development Research found uric acid blood levels in 20% of the 338 study participants with psoriasis. Here, researchers also found that psoriasis was the stronger predictor of hyperuricemia (high uric acid levels).

A large study published in 2015 aimed to determine whether people with psoriasis and PsA have a higher risk of gout than people without these conditions. This study included 98,810 people with psoriasis and/or PsA living in the United States who were followed over many years.

Here, researchers found the risk for gout was almost twice as high for people with psoriasis. People with both psoriasis and PsA had a risk 5 times higher.

The researchers noted while it was previously suspected that a link between psoriatic disease and gout occurred, this was the first time that risk was assessed in a large group of people with psoriatic disease.

These findings highlight the importance of doctors looking out for psoriatic disease complications and thinking about gout as a possible cause of inflamed joints even in the presence of psoriatic disease.

Causes

PsA is an autoimmune disease that results when the immune system malfunctions and targets healthy tissues, usually the joints and sometimes the skin.

On the other hand, gout is considered a metabolic disorder that causes the accumulation of uric acid in the blood and tissues. That build-up eventually triggers joint pain and swelling.

Psoriatic Arthritis

Researchers don’t know exactly what causes psoriatic arthritis. What they do know is that the immune system is involved in the development of both PsA and psoriasis.

Researchers believe gene changes may influence the development of PsA. The most studied genes linked to PsA are part of a family of genes called the human leukocyte antigen (HLA) complex.

HLA helps the immune system to distinguish the body’s proteins from those related to foreign invaders like viruses and bacteria. Variations in HLA genes seem to be connected to the development of PsA, as well as severity, type of PsA, and disease progression.

Family history also plays a role in PsA, and psoriatic disease tends to run in families. An inheritance pattern for PsA is unknown, but around 40% of people who get PsA have at least one close family member with psoriasis or PsA.

Environmental factors might also lead to the development of PsA. Injuries, infections, chronic stress, and exposure to toxins can also trigger PsA, especially in people with a family history of the condition.

Risk factors for PsA are:

• A family history will increase risk.
• Psoriasis: Having psoriasis is the greatest risk factor for PsA.
• Age: Anyone of any age is at risk for PsA, but it occurs most frequently in adults ages 35–55.

• Smoking: People who smoke have an increased risk for PsA. The connection between smoking and PsA is not direct but rather results from the chronic inflammation that smoking promotes.

Gout

There was a time when gout was called a “rich man’s disease” or the “disease of the kings.” It was thought to affect only wealthy men who consumed decadent food and drinks. Researchers know now that gout has to do with how much uric acid is in the blood as a result of diet choices, rather than the amount of money a person has.

Gout is also related to genetics. Studies have identified dozens of genes that play a role in triggering the condition. Of all the genes studied, two genes—SLC2A9 and ABCG2—seem to have the greatest influence on uric acid levels.

SLC2A9 generally provides instructions for making a protein found in the kidneys that manages the body’s levels of urate (the salt derived from the uric acid). Changes in this gene increase the reabsorption rate of urate into the bloodstream and decrease urate levels that exit the body through urine.

ABCG2 provides instruction for making a protein that helps to release urate from the body. Genetic changes to ABCG2 lead to elevated uric acid levels in the blood, which reduces the protein’s ability to release urate into the gut.

Nongenetic changes can also play a role in the development of gout and in triggering gout attacks. These changes increase the urate levels in the body, including the consumption of certain foods and beverages that contain high amounts of purines.  Purines are found in seafood, red meat, alcohol, and sugary beverages.

Risk factors for gout include:

• Being male: Males are 3 times more likely to have gout than females. This is because they have had high uric acid levels for most of their lives. Males usually produce less of the hormone oestrogen than females, and oestrogen helps remove urate from the body.
• Age: The risk for gout increases with age. In females, the risk of gout rises after menopause due to reduced oestrogen.
• Obesity: Having a body mass index (BMI) of 30 or more increases risk.
• Metabolic syndrome: This cluster of conditions increases your risk for heart disease, stroke, and type 2 diabetes. Metabolic syndrome includes high blood pressure, high blood sugar, excess body fat at the waist, and abnormal cholesterol or triglyceride levels.
• Decreased kidney function
• Congestive heart failure
• Genetics or family history
• Heavy alcohol consumption
• A diet high in purine-rich foods
• Excessive use of water pills

Diagnosis

There is no single test to identify PsA. High blood levels of uric acid might help detect gout, but that same blood work cannot rule out PsA. This is because people with psoriasis and PsA may have high uric acid levels and not have gout.

For both conditions, doctors will employ different testing methods to diagnose PsA or gout, including discussing symptoms and family history, examining joints, blood work, and other tests to rule out other conditions and similar diseases.

Psoriatic Arthritis

An accurate and early diagnosis of PsA is vital to avoiding joint damage and deformity. Diagnosis can be achieved by discussing symptoms and medical and family history, a physical examination, lab work, and X-rays.

• Symptoms: Your doctor will ask you about the symptoms you have experienced, what might cause them, and how long they last. The most telling signs of PsA are skin and nail symptoms.
• Medical and family history: Share with your doctor any medical record of psoriasis or family history of psoriatic disease.
• Physical examination: Your doctor will examine your joints and tendons for signs of swelling and tenderness. They will also check your fingernails for nail changes.
• Blood work: Erythrocyte sedimentation rate (ESR) indicates inflammation but is not specific to PsA. Rheumatoid factor (RF) and anti-CCP antibody testing help to rule out rheumatoid arthritis (RA), as these are high in RA but not in PsA. HLA-B27 testing looks for a genetic marker in PsA with spine involvement.
• Imaging: X-rays, magnetic resonance imaging (MRI), and ultrasound scans can show bone changes or joint damage. In people with PsA, doctors will look to the hands, feet, and spine as this type of joint damage can occur early in PsA.
• Joint aspiration: To rule out gout, your doctor will also request a joint aspiration. This involves using a needle to take a sample of joint fluid from one of your achy joints. If uric acid crystals are present, you probably have gout.

Gout

A diagnosis of gout is usually based on symptoms and the appearance of affected joints. Your doctor may also request tests to help diagnose gout and rule out other conditions:

• Joint fluid test: A joint aspiration is the most accurate test for diagnosing gout. Urate crystals will be visible when the joint fluid is examined under a microscope.
• Blood work: Your doctor will request a blood test to measure uric acid levels. Uric acid levels can be deceiving because many people will have high uric acid levels and never have gout, and some people have signs and symptoms of gout and have normal uric acid levels.
• Imaging: X-rays of affected joints can help rule out other causes of joint symptoms. Ultrasound can detect urate crystals in joints and tophi lumps. 

Treatment

As with most types of inflammatory arthritis, there is no cure for PsA or gout. But treatments for both conditions can relieve pain, reduce symptoms, and prevent failure.

Psoriatic Arthritis

Treatment for PsA will depend on how severe the condition, type of PsA, and if you already have joint symptoms.

One of the first treatments for PsA is nonsteroidal anti-inflammatory drugs (NSAIDs), such as Advil or Motrin (ibuprofen) and Aleve (naproxen), which are recommended for people with mild disease who have not yet experienced joint damage.

Conventional disease-modifying antirheumatic drugs (DMARDs), such as Trexall (methotrexate), are second-line therapies for people whose disease is active and who experience pain, swelling, and skin symptoms more frequently. These drugs work on the immune system to prevent damage to the joints, spine, and tendons.

For people who have experienced joint damage from PsA or whose symptoms are not managed by conventional DMARDs, biologics can be effective for slowing down disease progression. 

The newest treatments for PsA are Janus kinase (JAK) inhibitors, which work by tamping down the immune system to prevent joint damage and ease joint pain and swelling.

Additional treatment options for PsA can also help to manage your symptoms. These might include:

• Physical therapy to help you regain your range of motion, reduce symptoms, strengthen muscles, and stabilize your spine
• Topical treatments and phototherapy to treat psoriasis skin symptoms

Gout

Gout treatment focuses on reducing pain and the effects of gout attacks. Treatment also focuses on preventing gout complications by reducing the amount of uric acid in the blood.

Medications to help reduce symptoms of gout include:

• NSAIDs to reduce pain and swelling
• Mitigare (colchicine) to reduce inflammation and pain if taken within 24 hours of a gout attack
• Corticosteroids to relieve pain and swelling

Drugs that can help lower uric acid levels in your body to prevent or reduce future gout attacks include:

• Aloprin (allopurinol), given as a pill
• Uloric (febuxostat), given as a pill
• Benemid (probenecid), given as a pill
• Krustexxa (pegloticase), given as an intravenous infusion

While medication can be effective in the treatment of gout, you should also look to your diet to keep symptoms managed by:

• Choosing healthy beverages: Limit alcohol and drinks that are sweetened with fruit sugar.
• Avoiding foods high in purines: Red meats, organ meats (like liver), and purine-rich seafood (like anchovies and sardines) are all food items that can increase uric levels. 

Prevention

Inflammatory arthritis conditions like PsA and gout are rarely preventable. While researchers know that some people have a higher risk for these conditions, there are no treatments or preventive measures that guarantee you won't get PsA or gout.

Some people experience both PsA and gout. So, it is important to look for signs of gout if you have been diagnosed with PsA.

PsA flare-ups and gout attacks might be preventable and symptoms of both these conditions are manageable. Managing stress and diet, being active, and following your treatment plan are the best ways to prevent symptom flare-ups in both conditions.

Summary

Psoriatic arthritis and gout are two types of inflammatory arthritis that are sometimes confused because they share symptoms, including pain and swelling of the fingers and toes.

PsA occurs when the immune system malfunctions and targets the joints. Gout is the result of the build-up of uric acid in the blood.

Certain tests can help to tell PsA and gout apart including blood work and joint aspiration testing. These conditions are not always preventable, but they are manageable and treatable.

A Word From Verywell

If you experience joint pain or stiffness, seeing a rheumatologist can help you get an accurate diagnosis. A rheumatologist is a doctor who specializes in arthritis, other musculoskeletal conditions, and systemic autoimmune diseases.

While types of arthritis share symptoms, they are different diagnoses and can affect you in different ways. And while treatments can overlap, every type of arthritis should be evaluated and treated separately.

If you are diagnosed with PsA or gout, it is important to keep these conditions managed to protect your joints. Early and aggressive treatment can reduce joint damage and improve your quality of life.

https://www.verywellhealth.com/psoriatic-arthritis-vs-gout-5210250